A mysterious visitor appears, and Steve and Bucky get a midnight crash course on the workings of the universe before Steve gets big again.

Bucky woke up to a rush of cool air, opening his eyes to see Steve lifting his blanket up and clambering up onto his mattress. "Hey, Stevie," he yawned. "Whatcha doing?"

Steve wormed his way under Bucky's arm before he replied. "I had a bad dream," he whispered. He wriggled a little more to get closer and nuzzled his face into Bucky's chest.

"Yeah?" Bucky asked sympathetically. "Scary one?"

He nodded.

"Okay," Bucky said. He cinched his arm more securely around Steve. "Well, I gotcha now. You're safe."

"I know," Steve said softly, and something warm purred happily in Bucky's chest at the trust in his sleepy little voice.

"Go on back to sleep, buddy," Bucky said, patting his back. "I gotcha."

"Mmm," Steve hummed, already fading out. His breathing evened out, slow and peaceful in sleep, and Bucky followed suit, his eyes falling heavily closed.

A couple of hours later, Bucky woke up again, completely and instantly this time, sharp bells of warning going off in his head that something wasn't right. He sat up quickly, snatching up the knife under his pillow. He was aware of Steve grunting, "Mmf," unhappily as the sudden motion made him fall off of Bucky's back and face-plant into the mattress, but he ignored it for the moment, scanning the room.

For a moment, there was nothing, just the same darkness that had been there all night, empty but for him and Steve, and quiet but for the hum of air in the vents above. But for reasons he couldn't articulate, the energy of the room was off. Something was happening.

"W's goin' on?" Steve mumbled sleepily.

Before Bucky could answer, a spot of light appeared in the air, orange and steady and glowing, like a flame. "Get behind me," Bucky said, grabbing Steve's arm and yanking him around so that he was between Bucky and the wall.

The light started to move, drawing a thin circle of fire in the air. "What's that?" Steve whispered nervously.

"I'm not sure, but stay behind me," Bucky said, gripping the hilt of his knife tightly. He didn't know what was happening, but he recognized that light. It looked exactly like the portals from that warehouse—the ones that made the dragon creatures appear out of thin air. "F.R.I.D.A.Y., portal guy's back; call everyone else."

The A.I. did not respond, and the line of fire completed its circle. "There's no need to worry with that, Sergeant Barnes," a calm, feminine voice replied. A woman stepped out of the circle in the air. "I'm not here to hurt anyone."

"Uh huh," Bucky said skeptically, wrapping his metal arm a little more protectively around Steve and making sure he was all the way behind him. She was tall, thin and graceful, with a shaved head, almost translucently pale skin, and yellow robes that brushed the floor. She was smiling serenely. There was actually something nice and calm about her, but considering that she'd just opened a hole in the air and stepped through into his bedroom in the middle of the night, to say nothing of the fact that she seemed to have disabled F.R.I.D.A.Y. (and the security systems that came with her), Bucky wasn't buying it. "Sure," he said. "You just opened a hole in space into my room at three in the morning for, what, the view?"

She chuckled softly as the circle blinked out of existence behind her. "Well, there certainly isn't much of one right now, is there?" She waved a hand and the lights came on. "There," she said, folding her hands in front of her. "That's better."

"Who the hell are you?" Bucky demanded, eyeing the distance from the bed to the door and trying to gauge if he could grab Steve up and get around her and out the door before she tried anything.

"I am the Sorcerer Supreme," she said. "I and others like me master the mystic arts to protect this world from darkness." She smiled. "Something like your Avengers, simply on another plane of existence."

"Assuming I buy this whole wizard thing you have going on," Bucky said. "Protecting this world from darkness? Really? How exactly do flying alien fish-dragons trying to attack a city accomplish that? Not to mention what you did to Steve."

The woman's smile fell. "You're right, of course." She bit her lip thoughtfully, as if deciding how much to say. "The incident seven weeks ago was committed by one of our number. However, he turned his back on our ways, and stole from our sanctuary, seeking to use his knowledge and power for selfish gain."

Bucky stared, waiting for her to go on. It was easy to pin a problem on someone who wasn't there. He was going to need more than that.

"His summoning of the dragons was an attempt to gain leverage for something he wanted," she explained. "What happened to Captain Rogers was an accident."

"An accident?" Bucky asked incredulously. "How do you 'accidentally' focus your magic green glowy energy on someone and turn them back into a kid?"

"Perhaps I should have said it was not his initial goal," she said. "The Avengers showing up at what he had hoped to be a negotiation with me was not what he intended. What he did to Captain Rogers was a diversion to allow himself time to escape."

Steve was peeking curiously over Bucky's shoulder to watch the exchange, though his little fists were clenched anxiously in Bucky's shirt. Bucky didn't release his hold on him, but he patted his back in assurance. Assurance of what, he wasn't sure, because he still didn't understand what the hell was going on, but he wasn't going to let anything else happen to Steve.

"So what do you want?" Bucky asked.

"To make amends," she said simply. "It took longer than I care to admit to track our wayward colleague down. He is in custody now, however, and will not be causing anyone any more trouble. We have spent some time repairing the damage he did, and I have now come to finish it. Captain Rogers is the last piece of the puzzle."

It took Bucky a second to figure out what she meant. "You're here to undo what he did to Steve?"

"I am."

"Why?" Not that this wasn't what they'd been trying to do since the day it happened, but it wasn't as though Bucky had any reason to trust this woman.

"To return the universe to its proper course."

Well, that was a noble, if vague-sounding reason. "How do I know I can trust you?"

"I suppose you don't," she allowed, tilting her head to one side. "Though the fact that we are having this conversation at all proves something, I think. Had I meant you harm, I would have done it already." And that, Bucky didn't have any trouble believing.

"You came here to make me big again?" Steve asked, like he was making sure he understood what was going on.

"That's right," she said. She smiled warmly, beckoning with one hand. "Why don't you come out where I can see you?"

Bucky's grip on Steve instinctively tightened, though Steve didn't seem inclined to move anyway.

She sighed. "Sergeant Barnes, this must be done."

"Oh, must it?" Bucky asked. He pointed at her with his knife. "I don't care what kind of mystical, magical powers you have; you're going to have to give me a hell of a lot more before I let you lay so much as a finger on him."

"I commend your desire to protect him," she said. "But I must do this. The universe demands it."

Again with the universe and the vaguely noble-sounding sentiments. Was this woman capable of just giving a straight answer? "And what does the universe know?" he demanded.

She made a gesture with her hands, and little dials and pieces on the pendant hanging from her neck started to move, sliding aside to reveal a glowing green jewel. Steve gasped. Bucky shifted a little farther back, pressing Steve closer to the wall. The green light emanating from the jewel was something else Bucky had seen before—that was the same light that had surrounded Steve in that warehouse and made him small.

"This is the Time Stone," she said. "It allows me to see the flow of time. Past, present, and future. Sometimes the future is in flux—there are fewer things than one might suppose that are written in stone." She threw out a hand like she was tossing something up into the air, and suddenly there was a glowing orange web hovering above them, filling the room. The threads rippled and swayed, some staying in place, and some weaving in and out to create even more complex patterns. She pointed to one end of the web, where the filaments didn't seem able to move but were straining, stretching dangerously thin. "But right now, the strands that weave the future are starting to fray." She pointed at Steve, the web vanishing as she dropped her hand. "The universe requires Captain America to keep them intact."

Steve's jaw dropped open. "Me?" he whispered.

"Yes," she said. "You. But I'm afraid the universe doesn't have time to wait for you to grow into the hero waiting inside. We're going to need you sooner than that."

The room was quiet for a minute. "Okay," Steve said softly.

Bucky's eyebrows flew up in surprise. "Whoa, whoa, whoa!" he exclaimed. "No, Stevie, this—" Not that he disagreed that the world needed Captain America, but…Sorcerer Lady talked a good game, but she had yet to say or do anything concrete enough to make Bucky trust her. There were still way too many questions here, and he couldn't help feeling like she was taking advantage of Steve's willingness to do the right thing and his trusting nature. He turned around and took Steve's shoulders in his hands. "Steve, you really need to think about this."

Steve looked scared, but he shrugged. "What's there to think about? If the whole universe needs this an' this is what I can do to help, then, well, whether or not I want to doesn't really matter, does it?"

Skeptical of the sorcerer though he was, Bucky couldn't help smiling proudly at that declaration. "You really are a hero, aren't you?" he said softly, running a hand down one side of Steve's hair. "I just…" He looked back to where the woman was waiting patiently, then back at Steve. "I don't want anything to happen to you. I don't know if I trust her."

"I know," Steve said. He looked at her for a long minute over Bucky's shoulder. "But I do. I'm not sure why, but…I do."

Bucky sighed heavily. The kicker was, even though his head was vehemently fighting it, he did too, though he couldn't have said why. He didn't like it, but he believed her.

"Besides," Steve went on, smiling bravely at Bucky. "It'll be okay. 'Cause I'm just getting big—I'm not going anywhere. You said your friend was Steve Rogers, no matter what size, right?"

"Right," Bucky said softly.

Steve's smile widened. "Then it's okay. 'Cause we'll still be friends. I'll just remember more things. But I'll be here with you. I'm here 'til the end of the line too."

Bucky grabbed him into a hug, and Steve hugged him back tightly. "Okay," he whispered. He cradled one hand around Steve's little head. Assuming this woman was telling the truth, he was excited to get Big Steve back, but he was going to miss this little guy. But, like he'd said before, Steve was Steve no matter which way you looked at him—that brave, self-sacrificial little idiot that meant the world to Bucky.

"I love you, Bucky," Steve whispered, and there was a tremor in his voice that told Bucky just how scared he was, that he needed to make sure Bucky knew that in case this went wrong.

Bucky hugged him tighter. "I know," he said. He pressed a soft kiss to his hair. "I love you too," he assured him. Whatever happened next, that brotherhood between them was something the universe was never going to be able to change. He pulled back to look at him, smiling warmly. "I'll see you on the other side, okay?" he said, as reassuringly as he could manage, and he saw a little bit of confidence slip back into Steve's eyes.

"Okay," Steve said. He flung his arms around his neck one more time, squeezed tightly, then turned and slid off the bed. "Okay," he said to the waiting sorcerer. "I'm ready."

"Thank you," she said, smiling encouragingly. "Come and stand over here." She gestured to a space in front of her.

Steve shuffled over. "Is this…um…Is this going to hurt?" he asked quietly. Bucky had been wondering the same thing—another reason he'd been so worried to let Steve accept. He still remembered the way Steve had screamed the first time.

"No," she said, and she must have caught Bucky's incredulous eyebrow because she went on to explain. "This Stone can manipulate Time. When this was done to you, your personal timeline was reversed, reverting you back to a child. That in and of itself is not particularly difficult for one with our abilities. But the man who did this to you was no master of the Stone, and he was in a desperate hurry. He did not possess the skill or the time to do it as he should have." She smiled warmly. "I have both. While this may feel strange, I promise you there will be no pain."

Steve didn't look like he'd entirely understood everything she'd said, but he got the last part, and he nodded.

"Let's begin," the woman said. She made a sharp gesture with one hand, and the stone inside her necklace started glowing brightly. Green tendrils of light started at Steve's feet and slowly wound their way up and around his body. Steve's eyes widened in trepidation as they encircled him and started to lift him off the floor, but he stayed still. Bucky's fists were clenched nervously in the bedsheets as he prayed that he hadn't made a mistake in trusting her. This was just how it had started last time.

A ring of green light appeared around her left wrist, and she slowly began rotating it, manipulating her fingers back and forth in a complicated motion. At the same time, a ring of orange light appeared around her right wrist, and she started drawing little circles in the air with that hand, circles that had strange symbols inside.

Steve gasped and started moving like something had fallen down the back of his shirt and he was trying to shake it out. He didn't appear to be in pain, though, and Bucky couldn't help watching in fascination as his torso started stretching, his arms and legs slowly getting longer. What she'd been saying about Steve's personal timeline must have really been true, because he wasn't growing from little kid into Captain America, but into the skinny little adult he'd been before the serum.

Suddenly, they hit what must have been 1943 and Dr. Erskine and the serum, and everything just started…expanding. Bucky knew from Steve that Project: Rebirth had hurt like hell, and so he was grateful that the Sorcerer Supreme was keeping her promise and her weird little orange circle things were keeping Steve from feeling any pain. He was also very grateful, on Steve's behalf, that whatever she was doing seemed to be growing the clothes he was wearing right along with him—Steve wasn't ripping through them, or choking inside that little shirt collar, and he wouldn't be left lying naked on the floor when she was done. She was irritatingly cryptic, but at least she was thoughtful.

Steve stopped growing and changing, but she kept him hovering there a little longer, her hands still moving, like she was making sure she had gotten him all the way to twenty-nine or ninety-six, or however old he actually was now. The orange light disappeared, the tendrils of green started to uncoil, and Steve slowly sank back to the floor. He staggered a little bit when he landed, like he'd forgotten where the center of balance was for this much larger body, but he righted himself quickly. He looked down at himself like he was making sure of what he was seeing, then back up at her.

"Thank you," he said.

She smiled and inclined her head serenely. "You're welcome. Allow me to apologize once again for the behavior of my colleague. You can rest assured he won't be doing anything like that again." Her smile softened. "And thank you, Captain. Both for what you've done for this world, and for your willingness to do it."

She shifted to look around Steve and catch Bucky's eye. "You've handled this well, Sergeant Barnes. The world needs you too, you know." Before either of them could figure out what to say, she opened up a portal, stepped back through it, and vanished.

For a moment, the room was quiet, the two of them standing there and taking in everything that had just happened. Then Bucky laughed, shoved himself to his feet, and flung his arms around Steve. "Welcome back, Steve," he said.

Steve returned the embrace and pounded him on the back. "Good to be back, Buck. Good to be back."

Bucky pulled back and looked him up and down. "Are you okay? I mean, she said it wasn't going to hurt you, but…"

"Yeah, I'm fine," Steve assured him. "It felt…really weird, but it didn't hurt at all."

"I guess stretching out like that would be pretty strange."

"Actually, I barely noticed that part," Steve said. "It was mostly inside my head—like my life was a movie playing on fast forward. All these new memories and things were exploding into my head so fast I could barely keep up."

"But you remember everything now?"

"Right up to that warehouse and the weird green light." Steve looked down and scuffed his foot along the carpet, his cheeks coloring slightly. "I, uh, remember after that too. Being a kid and all."

Bucky looked at him quizzically. Was he embarrassed by that?

Steve looked up and caught the question in his eyes and sighed. "I was building castles out of cardboard boxes and coloring with crayons and running around pretending to be an airplane. Yes, it's embarrassing, alright?"

Bucky chuckled. "Okay, first of all, it wasn't your fault. Second of all, I guarantee you no one is going to think now that you're big again, you're still going to want a bedtime story. And third of all, it was adorable."

Steve kept blushing, but he smiled a little at that. "Is it weird that it was kind of fun? I mean, Little Me understood as much as he could, but he really didn't grasp how serious the whole thing was, and, believe me, I am so, so glad to be back, but…it was kind of nice for a little while."

Bucky smiled. He knew where Steve was coming from. Steve didn't have the easiest life, and there was no way to unplug from it completely. This really took the weight of the world off his shoulders for a while. "No, I get it," he assured him. "It was almost…restful."

Steve smiled, appreciating that he understood. "And, hey, you guys were great, by the way. Especially you. I mean, I…" He shook his head. "I was just a kid. I had this whole new century and way of life just thrown in my face, and you were…I felt safe with you."

Bucky smiled. "I'm glad. And you've been like my kid brother since you were three anyway, so, you know, I've had practice."

Steve laughed. "Yes, you have. Sorry if I was kind of a handful."

"Are you kidding?" Bucky teased. "You actually listened to me this time around. Seven whole weeks, and the closest you came to getting in a fight was when you were sick and argued about not wanting to eat dinner." He smiled. "This was practically a vacation."

Steve laughed again. "Thank you," he said, serious now, but still smiling. "Really, I…" He clapped Bucky warmly on the shoulder. "Thank you."

"Anytime," Bucky replied, smiling fondly. "Anytime." He grinned mischievously. "So, you keeping the jammies?" he asked, nodding at Steve's now adult-sized dinosaur pajamas.

Steve blushed again, laughed, and shook his head. "I'll think about it. They are comfortable, but if I end up keeping them, Tony will never, ever know that."

Later that morning at breakfast, there was all kinds of commotion over Steve being back, and he had to explain things several times since no one woke up at the same time, but eventually it settled and things started getting back to normal. Actually, it was surprising just how fast things got back to normal—in some ways, it was almost like it had never happened at all. There were a few things that stuck around, though, although no one ever actually put that into words, but they were…they were good things.

Stark still spent a lot of time sequestered away down in his lab, but Steve went down there more than he used to, just to check in and catch up. Bucky didn't know what they talked about, but some of those bricks Ultron had knocked out of the foundation of their relationship seemed to be back in place.

Afternoons where there wasn't a mission or anything important going on, it wasn't unusual to find Steve and Thor drinking tea and watching Chip and Joanna, engaged in a good-natured debate about the merits of tile versus hardwood flooring, rustic beams, open-floor concepts, and cabinet sizes. Steve still wasn't a fan of shiplap.

Natasha spent more time in the common area these days, being around people instead of off by herself somewhere. Wanda talked and laughed a little more freely, and seemed to be coming out of her shell. Sam was back to his morning runs with Steve, but now they would stop on their way back and have breakfast and talk. On mornings they didn't run, Steve would usually work his way into the kitchen to make breakfast with Clint. (Bucky wasn't positive, but he thought he heard the taco song one morning.)

All of Little Steve's clothes and toys had gone to charity…with the exception of Franklin the Second, who Bucky noticed tucked away on a shelf in Steve's room. He didn't say anything about it, but it felt nice that Steve had felt touched enough by his gift to hang on to it. And on nights when Bucky had a nightmare bad enough to bring Steve running from across the hall, neither of them said anything about the fact that the bear occasionally ended up on Bucky's nightstand, within reach if he felt like snaking an arm out from behind the wall of pillows Steve would build around him after he got him calmed down.

And if the nightmare was bad enough that Steve needed to stay after Bucky fell asleep, he would either curl up at the foot of the bed or stretch out on the floor beside it, which was just as well. Little Steve as a sleepy octopus was cute, but if Big Steve did it, it probably would have crushed him.

And so, we come to the end. I had a great time writing this, and I was kind of amazed that so many people enjoyed it so enthusiastically. You guys' support was awesome, and it meant an awful lot to me. Thank you!

As to what's next...I've got some Steggy stuff that's been simmering on the back burner for a while. Some of it's not ready yet, but some is, so that might be popping up before too long. And, of course, the Norseman's Cube sequel is always being worked on. And who knows what random fluffy ideas the muse will get in the meantime-that's where this one came from, and I'd say it worked out pretty well. :)

Thanks again! You guys are the best, and I'll see you soon!